Many font generating systems exist for generating Asian character fonts (“Asian fonts”). An Asian font is composed of a large number of ideographs that represent the characters in the Asian language. Asian languages may include thousands of characters. For example, the Chinese language includes over twenty-thousand distinct characters.
One conventional computer technique for generating character patterns in an Asian font uses font outlines. This system is described in “PostScript Language Tutorial and Cookbook” by Adobe Systems, Inc. (Addison-Wesley Publishing, 1985). In this method, the outline of a character pattern is stored as a collection of straight lines and curves. There are some disadvantages associated with this technique. First, because individual font outlines must be defined and stored for tens of thousands of different characters, the memory requirement is relatively high. Second, the font outlines that are stored in high resolution are suited for display only in high resolution; they are not suited for high-quality display in relatively low-resolution.
Another method of generating an Asian font uses stroke-based character pattern data, wherein each stroke within a character is separately defined. A character typically consists of multiple strokes that overlap or intersect with each other. The stroke-based character data consist of key points, width values, feature points, and curve ratios, which together define the outline of each stroke. The construction and rendering of such stroke-based character data are described in detail in U.S. Pat. Nos. 5,852,448, 6,151,032, and 6,157,390, which are explicitly incorporated by reference herein. The stroke-based technique is suited for reducing the memory requirements for fonts.
Yet another method of generating an Asian font uses glyph-based character pattern data, wherein each glyph within a character is separately defined. An Asian character typically consists of one or more glyphs, each of which in turn consists of one or more strokes. For example, several strokes in a character that intersect or overlap with each other often create a complicated overall geometric shape, which is a glyph. In the glyph-based technique, each glyph is defined in terms of key points, width values, feature points, and curve ratios, as in the stroke-based technique described above. The construction and rendering of the glyph-based character pattern data are described in detail in U.S. Pat. Nos. 6,501,475 and 6,661,417, which are explicitly incorporated by reference herein.
Still another method of generating a set of Asian fonts for display in gray scale is known, wherein each character comprises one or more strokes/glyphs, and each stroke/glyph is defined in silhouette-oriented representation. The construction and rendering of the silhouette-oriented representation for a display in gray scale is described in detail in U.S. Pat. No. 7,199,797, incorporated by reference herein.
With the advent of portable electronic device technology such as cellular phones, PDAs, and portable digital audio devices, relatively long binary text images are displayed, in smaller size, on the screen of such portable electronic devices. As these characters are typically defined to be displayed on a higher resolution screen, rendering these characters on a lower resolution screen causes severe degradation of the resulting text images. This is particularly true with Asian characters, which tend to have relatively more complicated overall geometric shapes. For example, FIG. 1A illustrates a character 10 superimposed on a low-resolution pixel matrix screen 11, and FIG. 1B illustrates an image of the character 10 as rendered on a low-resolution screen according to a conventional method (e.g., any pixel in which more than 50% of the pixel area is occupied by a character is activated/filled). As shown in FIG. 1B, the character 10, as rendered, is degraded to be almost unrecognizable. For example, strokes 12, 13, 14, and 15 of the character 10 of FIG. 1A have merged together to form a generally rectangular blob 16 in FIG. 1B. As another example, two similarly shaped components, B and B′, located on each side of a vertical stroke 17 of the character 10, are shown quite dissimilarly from each other, as C and C′ in FIG. 1B, when rendered on a low-resolution screen. FIG. 1C shows five Chinese characters, including the character 10 at the bottom, rendered on a relatively low-resolution display in degraded quality.
A need exists for a system, method, and computer-readable medium including instructions for generating or modifying fonts, which may have been originally designed for a high-resolution display, for high-quality rendering on a relatively low-resolution display.